False-positive results in screening for metallo-β-lactamase are observed in isolates of Acinetobacter baumannii due to production of oxacilinases

Martins, Andreza Francisco; Borges, Aline Morás; Pagano, Mariana; Dalla-Costa, Líbera Maria; Barth, Afonso Luís

doi:10.1016/j.bjid.2013.01.010

Cited by 4 publications

(3 citation statements)

References 8 publications

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“…baumannii as described earlier (Boran et al, 2015;Aksoy et al, 2015) and chelators (EDTA or MPA) may inhibit the dimers formation by OXA-23 (Martins et al, 2013). The results of double disc inhibitor (EDTA+IMP) based test have higher specificity (87.23%) than combined disc methods to differentiate OXA from MBLs.…”

Section: Rapid Molecular Identification Of Carbapenemase Genes Inmentioning

confidence: 83%

Detection of carbapenemases, AmpC and ESBL genes in Acinetobacter isolates from ICUs by DNA microarray

Uddin

McHugh

Roulston

et al. 2018

Journal of Microbiological Methods

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The accumulation of multiple inherent and acquired resistance mechanisms in Acinetobacter sp. results in emergence of "pandrug resistant" strains which is one of the major concerns in healthcare sectors worldwide. Surveillance of the carbapenemase/ extended-spectrum β-lactamases (ESBLs) genes in A. baumannnii by phenotypic methods is challenging especially in developing countries, like Pakistan. In this context, a novel microarray (CT 103XL Check-MDR) assay was used for simultaneous detection of genes encoding clinically important carbapenemases and ESBLs. The results were compared with the phenotypic methods including MHT, Rapidec Carba NP, EDTA+DDST and Rosco (KPC/MBL). The results of the microarray were also confirmed by PCR. All of the strains of A. baumannii (47) were resistant to imipenem and meropenem, while the other species of Acinetobacter were sensitive. Microarray and PCR results showed presence of OXA-23 in all the isolates of A. baumannii while 36.17% also harbored PER. Rosco kit test showed 100% sensitivity to detect carbapenemases but exhibited low specificity to classify them. Rapidec Carba NP test has 100% sensitivity and specificity to detect the carbapenemases when compared with microarray. Sensitivity and specificity of microarray assay were 100% for bla-genes in comparison to PCR. This reveals that Check-MDR CT103 XL assay is an accurate method for the identification of ESBLs and carbapenemase genes in A. baumannii in comparison to the other methods.

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Section: Rapid Molecular Identification Of Carbapenemase Genes Inmentioning

confidence: 83%

Detection of carbapenemases, AmpC and ESBL genes in Acinetobacter isolates from ICUs by DNA microarray

Uddin

McHugh

Roulston

et al. 2018

Journal of Microbiological Methods

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“…Primary resistance mechanisms responsible for resistance to carbapenems is because of the production of different types of carbapenemase enzymes, namely MBL, KPC, or Oxacillinases (OXA) enzyme [17,54]. The ethylenediaminetetraacetic acid (EDTA) or MPA is utilized in CDST to possibly chelate and inhibit OXA enzymes, after that, producing a result that could be interpreted as a false-positive for the presence of MBL [55]. One Bangladeshi study reported that carbapenemase genes were spotted in 11.6% among gram-negative pathogens in urinary tract infections and entirely gram-negative microorganisms’ community were carbapenemase-producing and were resistant to colistin.…”

Section: Discussionmentioning

confidence: 99%

Comparative Study of CDST & Multiplex PCR to Detect MBL Producing Gram-Negative Bacilli among VAP Patients Admitted in a Public Medical College Hospital of Bangladesh

Nusrat¹,

Akter²,

Haque

et al. 2019

Pathogens

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: Background: Ventilator-associated pneumonia (VAP) is the most common nosocomial infection in intensive care units (ICU), which accounts for 25% of all ICU infection. Documenting carbapenem-resistant gram-negative bacilli is very important as these strains may often cause outbreaks in the ICU setting and are responsible for the increased mortality and morbidity or limiting therapeutic options. The classical phenotypic method cannot provide an efficient means of diagnosis of the metallo-β-lactamases (MBLs) producer. PCR (Polymerase chain reaction) assays have lessened the importance of the phenotypic approach by detecting metallo--lactamase resistance genes such as NDM （New Delhi metallo-β-lactamase）, IMP （Imipenemase）, VIM （Verona integron-encoded metallo-β-lactamase）, SPM （Sao Paulo metallo-β-lactamase）, GIM (Germany imipenemase）. Objective: To compare the results of the Combined Disc Synergy Test (CDST) with that of the multiplex PCR to detect MBL-producing gram-negative bacilli. Materials and Method: A total of 105 endotracheal aspirates (ETA) samples were collected from the ICU of a public school in Bangladesh. This cross-sectional study was carried out in the Department of Microbiology, Chittagong for quantitative culture, CDST test, and multiplex PCR for blaIMP, blaVIM, blaNDM genes of MBL producers. Results: Among the 105 clinically suspected VAP cases, the quantitative culture was positive in 95 (90%) and among 95 g-negative bacilli isolated from VAP patients, 46 (48.42%) were imipenem resistant, 30 (65.22%) were MBL producers by CDST, 21 (45.65%) were identified as MBL producers by multiplex PCR. Conclusion: PCR was highly sensitive and specific for the detection of MBL producers.

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“…For 16 CDT positive strains, none of blaVIM, blaIMP, blaNDM and blaOXA-58 genes were detected. Several studies reported false MBL-positive results using this test, particularly in CHDLs strains likely due to chelators as EDTA that may inhibit the activity of oxacillinases [41,42].…”

Section: Molecular Detection Of Resistance Genesmentioning

confidence: 99%

Phenotypic and genotypic characterization of multidrug-resistant Acinetobacter baumannii isolated in Algerian hospitals

Benamrouche

Lafer

Benmahdi

et al. 2020

J Infect Dev Ctries

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Introduction: The aim of this study was to investigate the drug-resistance and the molecular characterization of carbapenemases, ESBL, and aminoglycoside-modifying enzymes among Acinetobacter baumannii clinical isolates in Algerian hospitals. Methodology: A total of 92 A. baumannii isolates were collected between 2012 and 2016. Antimicrobial susceptibility testings were performed for β-lactams, aminoglycosides, fluoroquinolones, trimethoprim-sulfamethoxazole, rifampicin and colistin. The phenotypic characterization of β-lactamases was investigated. For 30 randomly targeted strains, the carriage of the carbapenemases, ESBL and aminoglycoside-modifying enzymes -encoding genes was determined by PCR. Sequencing was carried out for carbapenemases and ESBL genes. Results: Most of the 92 isolates studied were recovered from hospitalized patients (93.5%) and were mainly from intensive care units (51.1%) and orthopedics (19.6%). The strains were collected primarily from low respiratory tract (33.7%), wounds (23.9%) and urine (16.3%). Multidrug-resistant A. baumannii strains were prevalent (96.7%). High rates of resistance were observed for almost all antibiotics tested (>70%) excluding rifampicin (7.6%) and colistin (5.4%). For the five colistin-resistant strains, MICs ranged between 4 and 128 µg/mL. Positive MBL (83.7%) and ESBL (23.9%) strains were identified. Regarding β-lactams, the blaNDM and both blaSHV and blaCTX-M1 genes were detected in five and two strains respectively. Sequencing of the genes revealed the presence of blaNDM-1, blaCTX-M-15, and blaSHV-33. For aminoglycosides, aac(6’)-Ib, ant(2’’)-I and aph(3’)-VI genes were detected in three, seven and six strains respectively. Conclusions: Here, we report the first co-occurrence of extended-spectrum β-lactamases SHV-33 and CTX-M-15, the carbapenemase NDM-1 and the emergence of colistin-resistant A. baumannii in Algerian hospitals.

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False-positive results in screening for metallo-β-lactamase are observed in isolates of Acinetobacter baumannii due to production of oxacilinases

Cited by 4 publications

References 8 publications

Detection of carbapenemases, AmpC and ESBL genes in Acinetobacter isolates from ICUs by DNA microarray

Detection of carbapenemases, AmpC and ESBL genes in Acinetobacter isolates from ICUs by DNA microarray

Comparative Study of CDST & Multiplex PCR to Detect MBL Producing Gram-Negative Bacilli among VAP Patients Admitted in a Public Medical College Hospital of Bangladesh

Phenotypic and genotypic characterization of multidrug-resistant Acinetobacter baumannii isolated in Algerian hospitals

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